Grading machine and equipment

ABSTRACT

The invention relates to a method and equipment for grading by thickness sensitive objects (particularly fish), large and small, involving gentle treatment of the objects, using ridge belts which are drawn by a drive along guides which are wider at the output end than at the intake end and covey the material gently without vibration or rubbing, together with infeed equipment.

The invention concerns a method and equipment for grading according tothickness sensitive objects (particularly fish, but also other organicand non-organic materials), involving more gentle treatment of theobjects, with a high processing rate.

The machinery and equipment involved is based on the assessment of thethickness of the objects, and is unique in that processing is based onspecially-designed conveyor equipment (hereinafter called ridge-belts)which move the objects forwards without shaking them or rubbing theirsurface in the course of grading. The equipment includes special ridges,tracks, adjustment devices, drive equipment, infeed equipment and theco-ordination of the functioning of all these elements in order toachieve the desired aims.

Many types and versions of grading machine for fish and other materialsare already known which grade the items according to an assessment oftheir thickness. These include machines with belts or rollers andshaker-graders with several grading channels. Like the ridge-beltmachine, the aforementioned machines all have grading channels that arewider at the outlet than at the intake. The belt machine draws theobjects forward between two inclined belts which form the channel, andif more channels are included in the same machine, each additionalchannel consists of an independent unit, i.e. another machine which isplaced next to the first one. The roller machines include two rollerswhich turn, the items being moved relatively slowly past the rollers bymeans of friction between the rollers and the objects. In the case of amulti-channel grader, additional machine units are placed next to thefirst one. The shaker-grader consists of ridges which form gaps, thecentral ridges serving two channels as in the ridge-belt machine, butthe objects are moved forward by being shaken, which throws the objectsup at the same time as the ridges are moved under the items, whichgradually moves them down across the grading frame. In addition to theaforementioned grading machines, there are machines which operate inaccordance with different principles and are fitted with electronicscales or imaging sensors. The aim in presenting the ridge-belt machineis to present a machine which treats the items to be graded gently, isaccurate, requires little maintenance and may be constructed so as tohandle extremely large quantities. The machine takes the form of aconveyor belt which neither shakes the objects nor rubs them in thecourse of moving them, but moves them gently forward until the pointwhere the gap becomes large enough for the object to fall through it.

The machine consists of a certain variable number of belts which arefitted with grading ridges, between which the grading gaps are formed.When grading is carried out in more than one size category, the gaps arekept narrower at the intake end of the machine that at the output end.By use of special adjustment equipment it is possible to widen or narrowthe grading gaps both at the intake end and at the output end. The driveequipment which drives the grading ridges is specially designed so thatit is possible to incline the tracks of the machine and make the gaps ofvarying sizes; in the case of the outermost tracks there is a highdegree of inclination when the machine is equipped with a large numberof grading gaps.

The infeed equipment ensures a high quality of grading, together withgentle treatment of the objects, while maximizing the utilization of themachine. To achieve this, the infeed equipment of the machine isdesigned so that the objects are in the optimal position before enteringthe machine, and the speed of the infeed to the grading gaps is similarto the speed on the grading ridges.

Through the interaction of adjustment devices, drive equipment, beltsand ridges, it is possible to arrange the infeed to a machine whichgrades accurately into many size-ranges according to thickness. Themachine can easily be set for objects in different size ranges, and itis easy to adjust the infeed equipment to the speed of the grader toensure that the quality of the grading is not diminished by a highprocessing rate.

The ridge belts run along guides which are formed by the ridge controlequipment. The ridges on the belts have sloping sides which direct theobjects to the edges of the grader. Both sides of each ridge belt areused in the grading, since there is one grading gap on either side ofeach belt; thus, the number of belts is only one greater than the numberof grading gaps.

Here follows a detailed description of the invention with reference tothe figures, which are as follows:

FIG. 1. A side view of the equipment designed for the grading of smallerfish species and relatively light objects.

FIG. 2. Top view of the same equipment as No. 1.

FIG. 3. A side view of the equipment designed for the grading of largerfish species or relatively heavy objects.

FIG. 4. Showing the ridge-belt guides for smaller fish and relativelylight objects.

FIG. 5. Showing the ridge-belts guides for larger fish species orrelatively heavy objects.

FIG. 6. Showing a ridge-belt for a light-construction machine forgrading small fish species and relatively light objects.

FIG. 7. Showing a ridge-belt for a heavy-construction machine forgrading large fish species and relatively heavy objects.

FIG. 8. Showing the setting pieces for setting the width of the gaps (instages) on a light-construction machine.

FIG. 9. Showing the setting equipment for a heavy-construction machinefor grading large fish and heavy objects.

FIG. 10. Showing the drive equipment for a light-construction machinefor grading small fish species and light objects.

FIG. 11. Showing the drive equipment for a heavy-construction machinefor grading large fish and heavy objects.

FIG. 12. Showing the tensioning equipment and anti-play equipment forheavy-construction grading machines.

FIG. 13. Showing infeed and distribution equipment for fish and otherlong objects.

FIG. 1 shows a side-view of the machine. The material to be graded islifted up into the step-channel (4). As it slides downwards, it assumesthe optimal position before sliding onto the ridge-belts (3). If thematerial is not adversely affected by contact with water, a water-pipe(5) is used to direct a film of water onto the step-channel, which makesthe material quicker to assume the optimal position. The gradient of thestep-channel (4) is set so that the speed of the material as it entersthe grading gaps is as close as possible to the speed of theridge-belts. The ridge-belts (3) run along belt-guides (2). The numberof ridge-belts may be from 2 to over 30 according to the processing raterequired of the grader. The guides are shown with an upward incline inthe figure, but they may be horizontal or inclined downwards, dependingon what is found suitable at any given time. Between the ridge-belts (3)are formed the grading gaps, the number of which is one fewer than thenumber of ridge-belts. The belt-guides (2) rest on the supports (9) and(10) with the adjustment pins (12). There are slots in the bottom of thebelt-guides, into which the pins are inserted, the interval between thesides of the slots and the pins being small. The number of theadjustment pins (12) on each of the supports (9) and (10) is one greaterthan the number of channels, and the interval between the pinsdetermines the width of the grading gap above the support. Support (9)is situated at the output end of the machine, while support (10) is atthe intake end. In the case of an extremely long machine, supports maybe added beneath the belt guides. The interval between the pins (12) onsupport (9) is larger than between those on support (10), resulting inthe grading gaps being wider at the output end than at the intake end.There are more rows of adjustment pins on each support, up to a total ofsix, each row having its own adjustment interval for the grading gaps.By turning the supports, another row of pins can be placed under theguide tracks, resulting in a change in the width of the grading gaps.The adjustment options thus consist of a series of steps, with moveablecross-plates (11) situated beneath the grading gaps to make precisedivisions between the size categories. The ridge-belts (3) are driven bythe drive drum (6), frictional resistance between the drum and the beltsbeing sufficient to drive the belts; if it is not sufficient, e.g. inthe case of long machines or heavy items, then the drum is covered withmaterial with a high friction resistance or with pins which engage inthe ridges and so drive them. Drum (7) is a free drum which guides thebelts into the guide slots in the belt guides. The drums rest on fourbearings (8).

FIG. 2 shows a light-construction grading machine seen from above,showing the motor (13) which drives the drive drum. It is desirable thatthe motor should be speed-adjustable, but whether it is a hydraulicmotor or an electric motor is immaterial. A gear motor may be used afterthe machine has been set and the material to be graded is always of thesame type.

FIG. 3 shows a side view of a heavy construction grading machine. Thismachine is considerably more powerful, and withstands greater loads,than the machine in FIGS. 1 and 2, which is designed for lightermaterial, but it operates according to the same principle. Theridge-belt guides (14) are made out of stronger material, and the wearsurfaces are made considerably stronger. They are also curved so thatthe ridge belts lie firmly and more heavily on the wear surfaces of thebelt guides and do not give under the lateral pressure of the material,even though this pressure is considerable. The ridges on the gradingbelt (15) are larger than on the machine shown in FIGS. 1 and 2, and itis more robustly constructed. The ridge-belts are driven by a cog-wheel(16) which engages with the links of the ridge-belt. A free cog-wheel(17) engages the ridge-belt as it leaves the belt-guides and guides itinto the belt tensioning equipment (18) and the anti-play equipment(19). The tensioning equipment removes all slack from the belt, whilethe anti-play equipment stops the belts being knocked about, e.g. onboard a ship at sea. The tensioning equipment and the anti-playequipment may be combined in a single unit. The adjustment equipment ona heavy-construction machine is considerably stronger than on thelight-construction version shown in FIGS. 1 and 2, as it is designed fora wide range of grading categories for heavy material and for use indifficult conditions. Each track is equipped with a runner (20) whichrests on the support (21) which holds up all the tracks of the machine;there may be many such tracks. The runner (20) has wear surfaces oflow-friction material in order to facilitate the movement of theridge-belt guides (14) when setting the grading intervals. The length ofeach runner (20) is such that the tracks rest solidly on the support(21) so that the grading interval is not upset by instability. Thepressure of the grading belts (15) on the curved belt guides (14) alsomakes the runners (20) lie firmly on the support (21). On machines witha large number of grading gaps, there are a large number of belt tracks(14), one more than the number of gaps. The length of the runners (20)is too great to make to possible to close the machine if they are linedup in a single row on the support (21). However, by positioning therunners (20) on either side of the support, it is possible to displacethem, in which case the channels can be screwed closer together; if thisis done, the grading range of the channels becomes very great, extendingfrom a closed channel up to 10-20 cm or more. When grading is performedin more categories, the grading gap must be wider at one end. Thus, thebelt guides (14) must be set at an angle, but without this influencingthe adjustment screws (22) and constraining them. The degree ofdisplacement increases as the tracks are located further from the centreof the machine, and is very considerable on the outer tracks. In orderto make this displacement of the tracks possible, the track (14) isconnected to the runner (20) by means of the rotational equipment (23).The adjustment screws (22) are located both at the intake end and theoutput end of the machine so that it is possible to adjust the width ofthe grading gaps both at the intake and output ends. The adjustmentscrews (22) have a right-hand thread at one end and a left-hand threadat the other. On the same adjustment shaft there may be screws withdifferent pitches and several sections of thread. On grading machineswith two channels, there is one adjustment shaft on either side, butwhen there are more channels, e.g. 12, two adjustment screws (22) areneeded on either side, with a drive in between them. As is stated above,the drive-wheel (16) drives the ridge-belts (15). The wheels (16) and(17) run in bearings attached to the appropriate track (14), whichensures that the alignment of the wheels is always the same as that ofthe grading machine. The drive axle (25) lies through the centre of thedrive wheels (16) of all the tracks of the machine. The axle (25) restson bearings at each end. The axle (25) is slightly loose in thewheel-holes, so that it is possible to set the drive wheels (16) atvariable angles to the centre line of the axle (25). The axle (25) andthe holes in the drive-wheels (16) are formed in such a way that theaxle drives the wheels easily despite the tracks running in differentalignments.

FIG. 4 shows the ridge-belt guide (2) for a light-construction machinefor grading smaller fish species and relatively light material. Theguides (2) are also shown in FIG. 1. They are made of H-sections with anadjustment recess (26) and a support recess (28). The H-section is madeof strong material such as aluminium or another material with sufficientsupport strength and wear-resistance to maintain a straight form underthe normal stresses resulting from the use of the machine. The guidechannels in the straight guides (2) are deep and provide good supportfor the light ridges which run along the running surface (27). The outersides of the H-section are inclined; thus, the grading gaps are slightlywider at the bottom so that the material falls off the sections eventhough it is soft or has stringy parts which tend to become entangled.

FIG. 5 shows a ridge-belt grader (14) for a heavy-construction machinefor grading large fish species and relatively heavy material. Theridge-belt guides, which are curved, are also shown in FIG. 3. Curvedguides have the advantage that the stress on the belt keeps the ridgespressed tightly against the track, which means that they withstandconsiderable lateral stress, e.g. from heavy pieces of fish, withoutbecoming inclined. The guides (14) are made of sections of flat steel orflat aluminium (30), which are connected with joints (31). On the upperedge of the guide there is a wear- and control edge (29) made of nylonor another wear-resistant and low-friction material. The control gap(32) is formed between the control edges. It is accurately measured,with a narrow degree of leeway.

FIG. 6 shows ridge links (3) for a light-construction machine. They arejoined to each other, forming a continuous ridge belt, or a sort ofchain. The ridge links (3) are cast out of nylon, with a pivot (38) madeof rust-resistant material. The ridge links having sloping sides (34)which guide the objects towards the grading gaps. The grading gaps areformed by the lower edges (35) of the ridge links. In the bottom of theridges there is an accurate guide (36) which runs along the guide-slotof the track (see FIG. 4) (26). The degree of leeway, ensuring that thegrading gaps have a high degree of accuracy. A recess (37) is moulded inthe bottom of each ridge unit, into which a cog tooth fits when theridge unit passes over the drive drum. The links described here may bemade out of other substances, such as metals or various types ofplastic.

FIG. 7 shows ridge links (15) for a heavy-construction machine. Theridge-belts (15) are formed by ridge links and connector links (41).These belts have larger ridges than the belts in FIG. 6, as they areintended for larger fish and heavier items. The ridge links (15) aremoulded from sheet metal or another mouldable material. They havesloping sides (34) which end at the bottom of the grading edge (35). Aguide ridge (40) extends downwards from the bottom of the ridge, andruns along the guide-slot of the track (32) (cf. FIG. 5). The gradinggap (42) is formed between two ridge links. It determines the thicknessof the objects which fall down. These ridge links may be made of othermaterials, such as nylon or plastic, if this is considered economicallyattractive. The connector link (41) is made of strong and wear-resistantmaterial such as steel or nylon.

FIG. 8 shows the setting- and support pieces (9) and (10) in alight-construction machine (cf. also FIG. 1), which hold up the gradingchannels. The setting- and support pieces (9) and (10) are made of areliable metal, and are sufficiently massive so as to have negligibleelasticity, in addition to which they are thick enough for it to bepossible to screw support and guide pins (12) into them from severalsides. The support pins (12) which are in use at any given time pointupwards, and the track guides (2) rest on them. On each setting- andsupport piece it is possible, e.g., to have 4-6 rows of guide pins (12),with a different interval between the pins in each row. When the settingand support pieces (9) and (10) are turned, a new row of support andguide pins is brought underneath the track guides (2) (cf. FIG. 1), thusaltering the interval. The support and guide pins (12) extend up intothe slots (26) in the bottom of three tracks (2). The interval betweenthe width of the slot (26) and the diameter of the support and guidepins (12) is so small that the track is held securely in place and theaccuracy of the measurement of the grading gap is very high. With thissetting equipment it is possible to have a great number of channels, ifdesired, e.g. as many as 40, with a correspondingly high processingrate.

The setting options available with the setting pins consist of a seriesof steps. More accurate settings are made on these machines by the useof cross-plates. By combining settings using the setting pins and thecross-plates (11) (cf. FIG. 1), the precision of the size categories canbe measured in fractions of a millimeter.

FIG. 9 shows the setting equipment for a heaving-construction gradingmachine. The track guide (14) is held up by a support (43). Arms for therotational equipment (44) extend out from the support, and from themextend the rotational plugs (23) which engage in bearings in the runners(20), which in turn rest on the support piece (21). When grading isperformed in more than one size category, the grading gap must be widerat one end than the other. Thus, the tracks (14) must be set at anangle, without this having an influence on the adjustment screws (22)and putting pressure on them. The further the tracks are away from thecentre of the machine, the greater the angle of divergence must be; thisproblem is solved by means of the rotational equipment. There may be aconsiderable number of runners (20) in machines with many tracks. Inorder to facilitate the shifting of the tracks when setting the gradinggap, the wear surface (45) on the runner is made of low-frictionmaterial. The length of the runner (20) is sufficient so that the tracksrest constantly on the support piece (21) to make sure that the gradinggap will not be influenced by instability. By positioning runners (20)on either side of the support piece (21), it is possible to screw thechannels closer together and make the grading range of the channels verygreat, extending from a closed channel up to 10-20 cm or more. Theadjustment screws (22), which are located at both the intake and outputend of the channel, go through the adjustment nuts (46), which areattached to the runner (20) to enable the width of the grading gap to beadjusted both at the intake and the output end. The adjustment screws(22) move the track guides, which are situated on each side of thecentre of the machine, towards or away from the centre; for this reasonthey have right-hand thread on one end and left-hand thread on theother. On the same adjustment shaft (22) there may be screws withdifferent pitches and several sections of thread when there is a largenumber of grading channels. On grading machines with two channels, thereis one adjustment shaft on each side, but when the number of channels isgreater, e.g. 12, there must be two adjustment shafts on each side withthe drive (47) in between. The aforementioned parts are made ofhigh-quality material such as aluminium, stainless steel or nylon, whileother materials may be selected if they are more economically viable.

FIG. 10 shows a light-construction machine with a drum drive. The drivedrum (6) pulls the grading belts (3) with the grading ridges along thetrack-guides (2). The drive drum (6) is fitted with teeth to ensure thatthe belts are pulled forward at the speed intended, or else are smoothbut are covered with a gripping material which provides sufficientresistance so that the belts (3) do not slip. The free drum (7) guidesthe grading ridges (3) into the belt-guide (2) so that they runsmoothly. A speed-controllable electric or hydraulic motor (13) isconnected to the axle of the drive drum. The speed of the grading ridges(3) is controlled by means of the motor so that it is as near aspossible to the speed of the raw material when it slides into themachine. The machine may be driven by a gear motor, in which case itwould be selected with reference to the average speed, but this optionis not recommended.

FIG. 11 shows the drive equipment of a heavy-construction machine. Thedrive wheels (16) in FIG. 3 drive the belts with the grading ridges.Teeth (48) are moulded into the drive wheel (16), and they engage withthe connecting links (41) (cf. FIG. 7). The wheels rotate in bearings(49) which are in arms (50) attached to the appropriate track equipment(14), so ensuring that the alignment of the wheels is always the same asthat of the grading belt. In the centre of the wheel there is a hole forthe drive axle (25), with moulded slots or grooves (51) with which thedrive equipment of the axle engages. The wheels are made of a reliablematerial such as nylon, stainless steel or other substances suitable formoulding cog wheels. The drive axle (25) runs through the center of thedrive wheels of all the tracks of the machine. The axle rests onbearings (8) at each end. The axle is slightly loose in the holes, so itis possible to set the drive wheels at varying angles to the centre lineof the axle. There is fluting, or there are wedges (52) on the axlewhich engage with grooves in the drive wheels and pull them.Alternatively, the axle could be made with an edged section (25), e.g.square in section, in which case wedges would not be necessary. The axleis driven by a speed-controllable electric or hydraulic motor (13). Agear motor may also be used, but this is not a desirable solution. Afree wheel (17) is situated at the other end of the machine (cf. FIG.3). The free wheel is equipped with the same sort of teeth as the drivewheel, and guides the grading belt (15) (cf. FIG. 3) from the guides andtowards the tensioning and anti-play equipment (14, 18 and 19) (cf. FIG.3).

FIG. 12 shows the tensioning and anti-play equipment, which removesslack from the ridge belts (3) (cf. FIG. 3) and ensures that there isnot lateral play on the slack part of the belt. The equipment is madeout of a U-shaped section (53) with hard-wearing, low-friction edges toreduce resistance. If it is found desirable, the tensioning (18) andanti-play equipment (19) may be combined in a single unit or divided upinto several parts (on the diagram it is shown in two parts). Thetensioning and anti-play equipment is constructed in a curved shape(catenary). By means of the tensioning screw or screws (54), it ispossible to press the anti-play and tensioning tracks downwards andtension each belt in the machine independently of all the others. Theanti-play tracks (19) support the lower part of the grading belts andprevent them from being knocked about, which is important, e.g. when themachine is used on board ship.

FIG. 13 shows the intake channel for fish or other long objects whichare to be graded by thickness. The intake channel (4) consists of two ormore steps. Three are shown in the figure. The uppermost step consistsof a smooth pan which receives the material from the conveyor device.The material becomes dispersed on the pan, and if it is not adverselyaffected by water, a water film is formed on the pan by a water sprayfrom the water-pipe (5). There are alignment pins (55) on the front edgeof the pan which align the material which slides down the pan, theinterval between the pins being determined by the type and size of theobjects. After the smooth pan, the next pans have corrugated surfaces,the spacing of the corrugation channels corresponding to the positioningof the grading gaps in the intake of the machine. There are alsowater-pipes (5) on the corrugated pans for use if the material to begraded is not adversely affected by water. There are also alignment pins(55) on the edges of the corrugated pans which align any objects whichmay have arrived with a transverse orientation after passing theprevious alignment pins. The overall gradient angle of the intakechannel is adjusted by altering the angle of the support pieces (56),which turn about a pivot (57), and the height is adjusted by means ofthe adjustment bars (58). The upper steps of the channel may be adjustedseparately by means of the adjusters (59) and (60). The alignment pins(55), the corrugations in the lower intake pans and the smooth pan atthe top of the intake channel, together with the water-sprays (5), areintended to align the objects correctly and direct them towards themachine's grading gaps. The gradient of the channel (4) and the settingof the water spray, where it is used, determine the speed of movement ofthe material and are used in order to made it the same as the speed ofthe grading ridges (3).

What is claimed is:
 1. Apparatus for grading sensitive products,comprising an in-feed device, ridge-belts for moving and grading theproducts, and guide rails for guiding the ridge-belts, the ridge-beltscomprising a plurality of units, triangular in cross section, andconnected to form endless belts guided by the guide rails from thein-feed device to remote end, the ridge-belts being spaced from eachother on the guide rails so that spacing of the ridge-belts is greaterat the remote end than at the in-feed device, the apparatus furthercomprising a setting mechanism for adjusting the distance betweenindividual guide rails, grading compartments under the ridge-belts, anda drive mechanism, whereby, in use, the products to be graded are fedonto the in-feed device and directed onto the ridge-belts that move andgrade the products according to thickness into the appropriate gradingcompartments, wherein the in-feed device comprises at least oneadjustable step for directing the products onto the ridge-belts so thatthe velocity of the products is controlled and orientation of theproducts is adjusted, and wherein the guide rails for the ridge-beltshave downwardly open slots into which support members of the settingmechanism extend, the position of the support members being settable bythe setting mechanism to determine the distance between the ridge-belts.2. Apparatus as claimed in claim 1, wherein the in-feed device comprisestwo or more steps each having an adjustable slope.
 3. Apparatus asclaimed in claim 1 or 2, wherein each step comprises a corrugatedsurface to guide the products to be graded.
 4. Apparatus as claimed inclaim 3, including alignment pins at the downstream end of the at leastone step for directing the products into an adjusted position. 5.Apparatus as claimed in claim 3, comprising means for directing acontrollable water flow onto the at least one step of the in-feeddevice.
 6. Apparatus as claimed in claim 1, wherein the guide rails areof H-shaped cross section to provide upwardly facing guiding slots, theridge-belts extending into the guiding slots.
 7. Apparatus as claimed inclaim 6, further comprising one or more turnable supporting beams havingsupporting/setting pins extending into the downwardly open slots in theguide rails to determine the distance between the guide rails and theridge-belts.
 8. Apparatus as claimed in claim 7, wherein thesupporting/setting pins extend radially from the supporting beams toform parallel rows of pins, and wherein the supporting beam is turnableto select one of the rows so that is pins extend into the lower slots inthe guide rails, whereby the spacing between the pins in the selectedone row determine the distance between the guide ails and theridge-belts.
 9. Apparatus as claimed in claim 8, wherein a predetermineddistance between the support/settings pins in each row on the supportingbeams determines the distance between the individual ridge-belts.